Expression analysis of cytokine coding genes in blood samples of clozapine‐treated patients with schizophrenia

Objectives: Dysregulation of peripheral immune responses has been detected in schizophrenic patients. Cytokines as the main regulators of immunological processes are also involved in brain development, which supports their putative role in the pathogenesis of schizophrenia. Methods: In the present study, we compared transcript levels of interleukin (IL)-1, IL-2, IL-6, chemokine (C-X-C) ligand 8 (CXCL8), transforming growth factor-β (TGF-β) and tumor necrosis factor-α (TNF-α) in the blood of 50 schizophrenic patients and 50 healthy participants. Results: IL-6 transcript levels were significantly higher in male participants compared with female participants (P = 0.005). TGF-β transcript levels were significantly higher in patients compared with healthy participants (P = 0.001). In addition, there was a significant difference in its expression between cases and controls based on the sex of the participants. TNF-α transcript levels were higher in male schizophrenic patients (P = 0.007) and in female patients aged <50 years compared with the age- and sex-matched healthy participants (P = 0.048). Transcript levels of other cytokines were not significantly different between cases and controls, which might be due to the effects of antipsychotic treatment in patients. Conclusion: The present study provides further evidence for abnormal transcript levels of cytokines in schizophrenic patients, as well as distinct regulation of cytokine expression in women and men. © 2019 Japanese Society for Neuroimmunology